- This topic has 7 replies, 1 voice, and was last updated 11 years, 6 months ago by Pix.
7th October 2009 at 08:39 #59090UrgentGuest
can somebody inform me the RF Load maximum value for S4/4/4 configuration by using 1*1 with Alcatel network,
Regards7th October 2009 at 11:21 #59091YasserGuest
Please can you give us your recommendation about this important question and thanks for Urgent,
Appreciate if you give the max value with different FP types,
Regards7th October 2009 at 21:37 #59092PixGuest
It’s very simple.
RF LOAD = (# of TRX in cell – 1) / (# of hopping frequencies in the cell)
(note : hopping frequencies are not including the BCCH frequency !)
This formula works for any kind of of SFH (1×1 or 1×3)
Now, depending on your SFH type, apply different thresholds :
if SFH 1×1, RF LOAD should be less than 12%. (max theoretical is 16% – but hard to achieve with a serious degradation of qos)
if SFH 1×3, RF load should be less than 30% (max theo is … 50% ? I forgot… anyway, theo limit is just a figure)
Hope it helps 🙂
pix7th October 2009 at 21:41 #59093pixGuest
4/4/4 in SFH 1×1, using 30 frequencies
RF LOAD = 3 / 30 = 10%
You are near the limit, so you should focus on down-tilting your antennas. The goal is to reduce at most the overlap between cells.
RF LOAD can be refined by replacing the # of TRX by the actual amount of (SDCCH + TCH) timeslots (in hopping TRXs) which are actually busy at the BH.
RF LOAD = (# busy TS @ BH / 8) / # of hop freq12th October 2009 at 21:57 #59094urgentGuest
I already implemented 1*3 with 6 freq. For s4/4/4 tch drop increased then we decided to change reuse type to 1*1 with 18 freq. tch drop decreased with sdcch drop increasing by more than 5% per network; diffrent cells not whole, and GPRS service stopped on gsm that i worked on! Yes TBF download became 10%!! and started at the same of frequency plan implementation!
Question: Freq. Plan could be areason for above problems? Alcatel network,
Regrads13th October 2009 at 04:56 #59095PixGuest
Have you read the formula below ? Did you apply it to your situation ?
Are you above the thresholds or below, in SFH 1×3 and SFH 1×1 ?13th October 2009 at 08:45 #59096YasserGuest
Hello pix and Urgent,
We already passed the threshold many time with both types and never we phased that types of problems! even the threshold passed will increase drop but not 5% per network,
and are the FP effect on the GPRS performance?
regards13th October 2009 at 19:35 #59097PixGuest
RF LOAD above the treshold will lead to bad drops. TCH is more resistant than SDCCH (thanks to AMR), so that’s perhaps why you’re seeing more SD Drops.
If AMR is not activated, then you can assume that people in the most interfered areas are always getting a SD Drop (or almost always). Statistics will show high SD Drop Rate. But TCH which are already allocated might be kept alive more succesfully, because people who managed to get a TCH are located in less interfered areas.
GPRS is of course impacted by radio frequency planning ! It’s even more sensitive than GSM !
If some cells don’t show bad QoS, it is because :
1/ they are not fully loaded (not all TS are busy at BH)
2/ they receive less overshoot from other neighbor sites.